The two buildings on the corner of First Avenue West and Fourth Street are known as the “Union Block,” though that name probably hasn’t been used much in the past 50 years.
On the street level are five businesses:
101 – Leroy’s Sweet Shop
103 – Hillside Laundry
105 – Sun Eagle Tattooing
107 – Da Houze of Flavor
109 – Twin Ports Upholstry

The Union Block has been owned by Franz Bier since 1998, according to city records. Michael W. Piper is the property manager and holds a lien on it. Piper and Bier both own other rental properties in Duluth.

Piper has long been known to house problem tenants. He was the first in the city’s history to be slapped with a fine in 2004 for tenant misbehavior. And while he also has had more complaints filed against his properties in the past five years than any other private landlord – 35 – he also has defenders who say that if it weren’t for him, many of his tenants would otherwise be homeless.

Some general history:

The building with storefronts 101-103 was built in 1890. The 105-109 building was built in 1883.

The 101 storefront was for many years the home of Fifty-nine-minute Cleanery (throughout the 1970s) and Madden’s Launderette (throughout the 1950s). Prior to that it was a drug store.

Hillside Laundry has occupied the 103 slot for at least two decades. It was the scene of the fatal shooting of James Alton Peterson on July 29, 2008. Terence Leon Callender faces first-degree intentional homicide charges in the incident. His trial is set to begin Jan. 18.

The 105 storefront was infamously the home of the Hip Hop Candy Shop four years ago. Owner James Redd was arrested on Oct. 6, 2006, for criminal sexual conduct. He was sentenced to 98 months in prison. He also had multiple arrests for selling crack and possessing marijuana.

DeeDee’s Doodads was in the 107 slot in 2007. The Diamond in the Rough diamond store preceded it. St. Louis Cash Market occupied the spot throughout the 1950s, ’60s and ’70s.

Twin Ports Upholstery has been at 109 for a while. St. Vincent de Paul Salvage held the spot for at least 20 years. There were a couple vending machine businesses before that.

I lived kitty-corner to this block for eight years, and called the police about once a week for various disturbances -- mostly fights. A famous one was back in 2005 where the whole block came out fighting with various pots and pans. I've witnessed car break-ins, drug deals -- often dealers would approach my car while I was sitting at the stop sign -- prostitution, general rabble-rousing. I also remember the Hip Hop Candy Shop blasting the radio 24/7 so Redd could listen to the police scanner under it when he was selling drugs. This was confirmed to me by the cops too.
Over the eight years, action waxed and waned, but it was always a hot spot for crime. I put it up to tenants who would only stay for a month or two and then move away, allowing criminals to come and go without background checks, etc.
I now live in a gentrified urban area of Seattle -- I can't tell you the amount of difference a well-lit street makes, as well as a positive neighborhood community that looks out for one another.

Repeating a comment from Da Houze of Flavor post and updating this old post ... and speaking of Leroy McGowan's Sweet Shop:
On Jan. 3, 2013, investigators from the Lake Superior Drug and Violent Crime Task Force and the Duluth Police Department executed a search warrant in the 300 block of N. Fourth Ave. W. -- about two and a half blocks from the old McGowan's Sweet Shop -- and seized crack cocaine, currency, and other evidence. Among the five suspects arrested and booked were Vincent Leroy McGowan and Loretta Ann McGowan.
On Jan. 7, they were formally charged by the St. Louis County Attorney's Office.
It should also be noted that Union Block owner Franz Bier was bought out by Michael, Kathleen and Phillip Piper, who in late 2012 sold the Union Block for $370,000 to the Housing and Redevelopment Authority of Duluth. It is part of a collaborative project being planned between One Roof Community Housing, Center City Housing Corp. and Churches United in Ministry to build a $12.8-million Section-8 housing development.